1. Field of the Invention
The present invention relates to an impurity eliminating apparatus for eliminating impurities on a surface of a substrate, a film forming apparatus, and a film forming method.
2. Discussion of the Background
For example, in a process of semiconductor device fabrication, a process for forming a SOG (Spin-on-Glass) film has been performed for an interlayer insulating film or flattening so far. Specifically, a treatment solution called sauce made by dissolving SiOx in alcohol is supplied onto the surface of a substrate such as a semiconductor wafer (referred to as "a wafer" hereinafter) and at the same time the substrate is spun to form a film by the treatment solution on the substrate surface. Thereafter, the substrate is heated twice to volatilize a solvent in the treatment solution and moreover baked. Thus, a predetermined interlayer insulating film is formed on the surface of a wafer and the substrate surface is flattened.
In a conventional process for forming a SOG film, after a wafer is taken out from a cassette storing wafers and carried to an apparatus in which a treatment solution is supplied and coated, for example, a spin coating apparatus so as to be coated with the treatment solution, the wafer is carried to a heating apparatus including a baking apparatus or a vertical type furnace where a predetermined heating treatment is performed for volatilization of a solvent and baking.
If the wafer itself taken from the cassette is, however, carried to the spin coating apparatus to be treated with the treatment solution as described above, so-called "wettability" is not satisfactory due to impurities such as organic substances adhering to the surface of the wafer and there is a possibility of causing problems in the subsequent fixing characteristic or fixing state of the SOG film. Besides, when the wafer W before forming the SOG film is in a state that the bottom corner portions of sidewalls 302 in a pattern 301 after being etched remain roundish as shown in FIG. 9, there is a possibility of exerting a bad influence on treatment for the wafer after having formed the SOG film, for example, formation of a conductive film, an oxidation insulating film, or the like.
Therefore, it is conceivable that the surface of a wafer is cleaned in advance, but in scrub cleansing or high-pressure jet cleaning used in a conventional film forming method such as a resist film forming method, organic substances on the wafer surface can not be fully eliminated and the aforementioned state that bottom corners remain roundish can not be solved. In addition, a process for drying is required thereafter, which is undesirable in respect of throughput.